schultz



Sept- 7, 1943-, l w. SCHUL-rzl Re. 22,372y

l v I FUSE original Filed April 24. -1959 4 Asmaemsl-jsmwt 1 W. O. SCHULTZ sept. l7, 1943.

4 Sheets-Sheet 2 riginal Filed April 24. 1939 INVENTOR.

ATTORNEY Reuma sept. 1, 194e- Re. 22,372y

UNITED sm'rlzs, PATENT OFFICE l FUSE wimamo. schuim, south Milwaukee. wis., as-

` signor to Line Material Company, South Mib' waukee, Wis., a corporation of Delaware Original No. 2,249,178, dated July 15, 1941, Serial No. 269,613, April 24,v 1939. Application for reissue June 17, 1943, Serial No. 491,248

(Ci. 20G-116) 24 Claims.

This invention relates to fuses and is particu- -novel means are provided for very quickly and forcibly extracting any remaining unburned portion of the fuse link, such means causing the fuse link to be withdrawn substantially in line with the fuse tube, thereby overcoming any tendency of sticking due to the link dragging over the end of the tube, and also permitting the use of rela.- tively stifi' fuse link leaders.

drawai of the fuse link occurs on either heavy or light overloads, and in which this operation is perfonned very quickly.

An embodiment of the invention is shown in the accompanying drawings in which:

i igure 1 is an elevation of the device, partly in section, showing the fuse in operative position.

In greater detail, further objects are to provide a flip-out andy fuse tube releasing device which is so made that it quickly and forcibly ejects the unburned portion of the fuse link,

thereby causing a quick interruption of the cir.

cuit within the fuse tube itseli', and which thereafter releases the fuse tube and allows the fuse tube to slide downwardly to inoperative position out of the electric circuit.

Further objects are to provide a fuse construction in which a quick operating flip-out device is provided for withdrawing any remaining portion of the fuse link, in which this flipout device, due to the momentum acquired by it in fuse extracting motion upon rupture of the fuse link, transmits force to a, retaining lever by the momentum of .the flip-,out device itself and assists in rocking the lever to fuse releasing position, the lever being biased towards fuse releasing position by the weight of the fuse tube and by the pressure of an upper spring contact.

Further objects are to provide a construction in which the flip-out device acts as a spring cushioning means for taking up any slack in the fuse link after refusing and which acts as a cushioning member when the door of the fuse device is suddenly closed, thereby preventing the transmission of any undue kstress to the fuse link itself.

Figure 2 is a sectional view on the line 2-2 of Figure l.

Figure 3 is a face view of the lower portion of the door and the associated parts detached from the housing.

Figure 4 is a side elevation of the device. Figure 5 is a bottom plan view of the structure. Figure 6 is a sectional view on the line 9 6 of Figure 1.

Figure is a. view of the lower portion of lFigure l, showing the parts as they appear after the fuse has blown.

Referring to the drawings, it will be seen that the fuse comprises a casing I of porcelain or other suitable material which is provided with hooks 2, see Figure 7, adjacent its lower portion. The hooks removably receive the headed trunnions 3 of a door 4 formed of suitable insulating material, such as a phenolic condensation product. The door is provided with an eyelet portion 5 by means of which it may be opened or closed, and with a. web 6 on its inner side having a rounded portion to accommodate the upper cap 'l of the fuse tube 8.

The housing carries an upper terminal meinber indicated generally at'S and a lower terminal member indicated generally at lli. 'I'he upper and lower terminal members are provided with conductor receiving portions, as shown, and the conductors may extend outwardly through the usual apertures,v in the sides of the housing.'

' orv contact is provided with a contact .spring4 I2 Further objects are to provide a drop-out fuse f of the sliding type which is so constructed that there is .no chance of the fuse sticking in place after the fuse link has been ruptured, in which a complete interruption oi the circuit and withwhicn may befonned of laminated structure, as shown, and one end of the spring may be folded over, asindicated at Il in Figure 1. The spring has a flat lower portion that bears firmly against the upper flat face of the cap 'l of the upper contact of the fusel tube. This upper terminal is also provided with a pair of relatively heavy spring arms I4, as shown in Figure 2, and these arms are provided with inwardly depressed portions I5 which t around in front of the upper cap 1 of the fuse tube. The arms I4 do not bind against the upper cap of the fuse tube. However, they assist in holding the door in closed ture, as shown" in Figure 6. A,

The door rigidly carries a4 lower or sleeve I8, see Figures 1, 3, 6 and 7.4 This sleeve or lower contact of the fuse tube is providedv with bevelled portions .I9 to assist in spreading the spring arms I6 of the lowertermlnalmember.

beneath a. forwardly projecting, overhanging ear 2| carried by the lower terminal to `provide a l stop for resisting the tendency towards upward recoil when the fuse blows.

The lower contact I8A carries a U-shaped lever 22, see Figures 1 3 and 7, which lever in turn pivotally carries ar flip-out device 23, see particularly Figures l and 7. The ilip-out device is mounted upon a pivot pin 24 extending across the lower portion of the lever 22, and a spring 25 is loosely coiled `about the pin and bears against the nip-out and against a portion of the lever urging.

the flip-out towards clockwise rotation, as viewed in Figure 1.

'I'he iiip-out is` preferably provided with ya slightly rounded front `edge portion 26 and with a. rounded rear edge portion 21, and with a pair of lips 28 on opposite sides of the rear edge portion. These lips are adapted to engagethe laterally projecting bottom side portions 22 of the lever 22 after the flip-out has operated, as shown in Figure 7. i l

contact block' 'I'he contact I8 is also provided with-a rearwardly projecting ear 20 which is positioned laminated strucv.

The pin 38 normally bears against the shouldered portion 23 of the lever 22'. It is to be noted. however, that the pivot point 39 of the lever -22 is spaced laterally from the shouldered portion 29 so that when the tube is freed by rupture of the fuse link, the weight of the tube together with the spring pressure` eiterted by. lthe upper contact spring I2k will rock the lever 22 to the left, as viewed in Figure 1, and thus release the tube for downward sliding motion, the nal position of the parts being shown in Figure 7.

It is to be noted particularly that the ipper 23 in rocking about the pin 24, causes its outer or free end adjacent the bottom of the fuse tube` to rock substantially straight downwardly for `a portion at least of' its stroke and consequently it is 'possible to use stiier leaders with this construction as it does not require the making of a sudden bend in the link when the flipper operates, particularly in the early portion ofthe stroke of the flipper.

Additionally, it is to be noted that the flipper executes a veryquick stroke and quickly `interrupts the circuit within the fuse tube and forcibly withdraws the remaining portion of the fuse link and avoids any tendency of sticking or binding of the leader at the lower end of the fuse tube for, as stated, the flipper executes a stroke'which The contact sleeve I3 isprovided with stops I8' Y for limiting the outward motion of the lever 22..

in Figures 1 and 7. 'Ihs metal sleeve loosely and' slidably ilts within the sleeve I8 ilxedly4 carried bythe door. It is provided to prevent any possibility oi' binding of the fuse tube within the sleeve I8 in the event the fuse tubeshould swell, and

insures free sliding ofthe fuse tube through the` sleeve under all conditions. .l

.Normally the fuse tube is held in place in its upper position, as. shown in Figure 1, by means of ali'use link which includes the fusible section 33 and a leader 3l. The leaderextends outwardly through -the bottom open end of the fusetube and y'is guided through the notch 35 formed in` the bottom marginal portion of the fuse tube and extends over the flipper 23 and upwardly to a position below the thumb screw 36, the thumb screw 3B being screwed on a threaded stemf31 rigidly `carried by the lower contact or sleeve I8. The sleeve 32 is locked to the fuse tube by a transversely extending pin 3,8 which passes through thesleeve andv through a notched portion o1` the fuse tube, not shown, and which has inturned ends to prevent its lateral displacement. The inturned endsare most .clearly shown in Figure 5`.V V f is substantially downwardly with reference to the lower end of the fuse tube and thereby projects thelink in substantial alignment with the fuse tube.

It is to be noted further as shown in the dotted line position oi Figure 7, that the momentum of the iiipper when the flipper is brought to rest by the contacting of its fingers 23 with the adjacent portion of the lever 22, assists in throwing the` lever 22 to the left. as viewed in Figure 7, and as shown in dotted lines, so'that this action assists the action of the fusetube in disengaging itself from the lever 22.

A further advantageous result from this construction is due to the fact that inevitably there is some slack in the fuse link when it is clamped beneath the clamp thumb screw 36. Therefore, if vthere is any shock imparted to the link by slamming the door` shut, the flip-out device acts asa spring buffer torelieve or cushionany shock to the fuse link. y

It will also be seen that the flipper operates immediately prior to the sliding downwardly of the tube and as there is very little inertia to the ipper in comparison to the inertia to the other parts, it is obvious that the flipper will execute a yvery quick stroke and quickly interrupt the cir- Further, the ilip-out device if desired may be carried on the pivot link which pivot vlink is pivotally carried by supports at its lower end and is pivoted to the Yfuse tube at its upper end. This last construction is specifically claimed in my copen'ding application Serial No. 307,350, led Decernber 4, 1.939, forFuses.

Althoughthis invention has been described in considerable detail, vit is to be understood that such description is intended `as illustrative rather than limiting, as the invention may be variously means having a stationary upper contact and a lower contact, a fuse tube having an upper contact normally engaging said stationary upper contact and having an open lower end, a fuse link extending from the upper contact o! said fuse tube outwardly from the open end and electrically connected to said lower contact, said fuse tube being'movably supported from said support and movable from operative to inoperative position, movable latching means adjacent the lower portion oisaid fuse tube for normally holding said fuse tube against motion from operative to inoperative position, and a ilip-out device carried by said latching means and over which said fuse link is looped, said flip-out device being biased towards iuse link extracting motion and having .motion with respect to said latching means independently oi any motion of said latching means.

`2. A drop-out fuse comprising supporting means having a stationary upper contact and a lower contact, a iuse tube having an upper contact normally engaging said stationary upper contact and having an open lower end, a fuse link extending from the upper contact of said fuse tube outwardly from the open end and electrically connected to said lower contact, said fuse tube being movably supported from said supporting means, movable latching means adjacent the lower portion of said fuse tube for normally holding said iuse tube against motion, a ilip-out device pivoted on said latching means and engaging a portion of said iuse link, and a spring urging said flip-out device towards fuse link extracting motion, said nip-out device withdrawing any unburned portion oi' said fuse link outwardly from said fuse tube substantially in line with said fuse tube.

y 3. A drop-out fuse comprising supporting means having a stationary upper contact and a lower contact, a fuse tube having an upper contact normally engaging said stationary upper contact and having an open lower end, a fuse link extending from the upper contact oi' said iuse tube outwardly from the open end and electrically connected to said lower contact, said fuse tube being movably supported from said support, movable latching means adjacent the lowr portion of said fuse tube for normally holding said fuse tube against motion, a nip-out device pivoted to said latching'means, and a spring engaging saidiiip-out device and-said latching device and urging said nip-out device towards motion with reference to said latching means.

4. A drop-out -fuse comprising a support having an upper stationary contact and having a lower contact, a fuse t'ube slidably mounted in said lower'contact and having an upper contactv normally engaging the upper contact of said support and movable away therefrom when said fuse tube slides downwardly, alatching lever normally restraining said iuse tube against sliding, a spring biased flip-out lever pivoted on said latchingl lever, land a fuse link extending from the upper `contact o! ysaid fuse tube through said fuse tube to said lower contact and secured to said lower contact, said link being looped over said nip-out lever.

5. A drop-out fuse construction comprising a support having an upper ystationary contactand a lower contact, a fuse tube slidablymount'ed in nld iowercontact and having an upper contact adapted to normally engage the upper stationary contact and movable away from said-upper stationary contact when said fuse tube slides downwardly, said fuse tube having an open lower i end and having a projecting portion. a latching lever mounted on said lower contact and'normally engaging said projecting portion to restrain said fuse tube against sliding motion, a spring latching lever and said flip-out lever.

6. A drop-out fuse construction comprising a support having an upper stationary contact and having a .lower contact, a fuse tube slidable through-said lower contact and having projecting portions on opposite sides of said fuse tube, a U-shaped latching lever pivoted to said lower contact and having shoulders onv opposite sides normally engaging said projecting portions and restraining said fuse tube against sliding motion, a nip-out lever pivoted adjacent the lower portion of said latching lever, a spring between said latching lever and said flip-out lever urging said flip-out lever towards outward motion, and a fuse link extending from the upper contact of said fuse tube to the `lower contact and looped over said ilip-out lever, said nip-out. lever having a free end adjacent the lower portion of said fuse tube for extracting any remaining portion of the fuse link in a direction substantially in line with wardly from the lower end of said fuse tube, a.

pivotally mounted latching lever having shoulder means, projecting means carried by said fuse tube -and normally engaging the shoulder means of said pivoted latching lever, a ilip-out lever pivotally mounted adjacent the lower end'of said latching lever and over which said fuse link is looped, and va spring between said latch lever and said pivoted flip-out lever urging said pivoted p flip-out lever towards fuse link extracting motion, said nip-out lever having a portion adapted to engage said latching lever upon completion o! the outward stroke of such -iiipout lever,

whereby the momentum oi said flip-out lever -will tend to rock said latching lever to releasing posi- 8. A drop-out fuse construction comprising a support having a stationary upper contact and having a lower contact, a fuse tube slidably mounted within said lower contact and having an open lower end and aclosedupper end provided with an upper contact normally engaging said stationary upper contact, a latching lever, said fuse tube and said latching lever having normally interengaging parts to restrain said fuse tubeagainst sliding motion, said latching lever being pivoted to said lower contact at a point spaced from said interengagins parts, whereby the weight of said fuse tube tends to vrock said latching lever to latchreleasing position,a spring kbiased nip-out lever pivotally mounted on the link extending from thelupper contact of said fuse tube outwardly from the lower end thereof to the lower contact and looped over sa'id flip-out lever.k

, `Si. A drop-out fuse construction comprising a support having a stationary upper contact and having `a lower contact, a fuse tubeslidably mounted within said lower contact and having `an. open lower end and, a closed upper end provided with an` upper contact, normallyengaging said stationary upper contact, a latching lever,

said fuse tube and said latching lever .having normallyinteren'gaging `parts to restrain said fuse tube against slidingmotion, said latching lever being `pivoted to saidL lowencontact at a. point spaced from saldil interengaging parts, whereby the weight of said fuse tube tends to rock said latchingy lever to llatch releasing position, a spring biased iiip-out lever pivotally mounted on the lower portion of said latching lever, and a fuse link extending from the upper contact of said fuse tube outwardly from" the lower end thereof to the lower contact and looped over said flip-'out lever, said flip-outflever having a yquick fuse link extracting motion independent of the motion of said latching lever.

10. A drop-out fuse construction comprising a support having a stationary upper contact and having a lower contact, a fusetube slidably `mounted within said lower contact and having an open lower end and a closed upper end prol vided with an upper contact normally engaging said stationary upper contact, a latching lever, said fuse tube and said latching lever having normally interengaging parts to restrain said fuse tube against sliding motion, said latching lever being pivoted to said lower ,contact at a point spaced from said intere'ngaging parts, whereby the weight of said fuseA tube tends to rock saidflatching lever to latch releasing position, a spring biased flip-out ,lever pivotally mounted on the lower portion of said latching lever, and a fuse linky extending from the upper contact of said fuse tube `outwardly from the lower end thereof to the lower contact and looped over said flip-out lever, said flip-out lever having a quick fuse link extracting motion independent of `the motion of said latching lever, andfsaid latching lever being movable outwardly after said flip-out lever hasoperated `to assist in the further extraction oi any remaining portion of said fuse link upon rupture of the fuse link.

11.` A drop-'out vfuse construction comprising a support having an upper stationary contact and a4 lower contact, a fuse tube slidably mounted in said lower contact and having an upper contact normally engaging `said stationary upper contact, said fuse tube having laterallyproiecting portions, a YU-shaped latching lever pivoted on opposite sidesy to said lower contact and having shouldered portions spaced llaterally, from the -pivot and`normally engaging the projecting "portionsfoi said fuse tube,a channel-shaped flipout lever pivoted adjacent the lower portion of .t tionary contact, a fuse tube slidably carried .by

the contact oi' said door and having an upper contact normally engaging the upper stationary contact, a latching lever pivoted to the contact of said door, said latching lever yand4 said fuse tube havinginterengaging portions normally restraining said fuse tube against sliding motion,

a ilip-out lever` carried by the latching lever and spring urged `outwardly with reference to said latching lever, and a fuse link extending from `the upper contact of, said fuse tube over said flip-out lever to the contact carried by said door. 13. A housed vtypef-drop-out fuse comprising a housing having upperand lower stationary contacts, a door.pivotally mounted 'onr said'housing and having a lower contact, adapted to engage the stationary lower contact, afuse tube slidably mounted in the contact of said door and having an upper contact adapted toengage the uppery contact of said housing, at least one ofthe con-- tacts of ysaid housing having inturned ends adapted to normally prevent opening of said door, a vlatching lever pivotally mounted on the contact ofsaid door, said latching lever and said fuse tube having normally interengaging vportions, a spring pressed ilip-out lever pivotally carried by the lower portion of said latching lever and havinga free end positioned' adjacent said latching lever, a iuselink extending from the upper contact-of saiduse tubeto the lower contact and looped `oversaid flip-out lever, and

a spring urging said flip-out lever towards outotally mounted on saidy housing and having a lowerl contact adapted to enter between the arms or" said vlower stationary contact and n having shoulderedportions adapted to seatback of the s inturned endslofv the arms'of said lower stathe-lower end of said fuse tube, and a fuselink extending from the upper contact of said fuse tube over said ilip-out lever tothe contact carried by said door.

. 14:.` A housed type drop-out fuse comprlsin-g housing having upper and lower stationary contacts, a` door pivotally mounted on said housing and having a lower contact adapted Ato engage the stationary lower contact, a fuse tube slidably mounted in the contact of said door and having an upper contact adaptedto engage the upper contact of said housing, atleast one of.'

the contacts of said housing having inturned ends adapted to normally prevent opening of said door, a latching lever pivotally mounted on the contact of said door, said latching lever and said fuse` tube `having normallyy interengaging portions, a spring pressed flip-out lever pivotally carried by the lower portion of said latching lever and having a free end positioned adjacent the lower end of said fuse tube, and a fuse link extending from the upper contact of'said fuse tube over said iiip-out lever `to the contact carried by said door, said upper contact including a spr/ing normally `bearing downwardly on the upper contact-fof said fuse tube.

15. A housed `type' drop-out -fuse comprising a housing having upper and lower stationary .con-

tacts, a door pivotally mountedon said housing i andV havingla lower contact adapted to engage the stationary'lower contact, aiuse tube slidably mounted in the contact of said door andhaving` an `upper contact adapted to engage "the upper contact of said"housing, at leastone of the contacts yof said housing"` having `inturned ends adaptedto normally prevent opening 'of said door, af latching lever pivotally` mounted onthe contact of said door, said latchingflever and said fuse tube ,having` normally interengaging portions, a spring pressed dip-out lever pivotally carried by the lower portion of said` latching lever and having a` free end positioned adjacent the lower end `of said fuse tube, and a fusey link extending fromA the upper contact of said fuse tube over said flip-out lever to the contact carried by said door; said upper contact including a. springnorrnally bearing downwardly on the up- Ling support having terminals, the combination with an expulsion per contact f said fuse tube, said lower stationary contact and the contact carried by sa-id door having means adapted to interengage and to prevent shlfting of said door due to recoil upon blowins of said fuse.

16. A fuse construction comprising supporting means having a stationary upper contact and a lower` contact, a fuse tube having an upper contact normally engaging said stationary upper contact and having an open lower end, a fuse link extending Ifrom the upper contact of said fuse tube outwardly from the open end and electrically connected to said lower contact, a flipout device pivoted adjacent the lower portion of said fuse tube and extending substantially transversely of the axis of said fuse tube, said flipout device having a free end engaging a portion of said fuse link and adapted to extract any unburned portion of said fuse link with a substantially downward motion from said fuse tube and being movable without requiring the motion of any other portion of the fuse construction. and means for urging said nip-out device towards fuse extracting motion independently of motion. of other portions of the fuse construction.

17. In a fuse construction including an insulata pair of relatively spaced fuse cartridge normally bridging said terminal and having at least one end open, a mounting for said cartridge pivotally supported by said support, a first lever pivotally carried by said mounting adjacent the open end of the cartridge, a spring biasing the first lever for pivotal movement, a second lever pivotally mounted on the free end of the first lever, a second spring biasing the second lever for pivotal movement independently of the pivotal movement of the first lever, and a fuse link in said cartridge electrically connecting said terminals and normally holding said levers against movement by said springs.

18. In a'fuse construction including an insulating sup-port having a pair of relatively spaced terminals, the combination with an expulsion fuse cartridge normally bridging said terminals and having at least one end open, a mounting for said cartridge pivotally supported by said support, a first lever pivotally carried by said mounting adjacentthe open end of said cartridge, a spring biasing the first lever for pivotal movement, a second lever pivotally mounted on the free end of the first lever, a second spring biasing the second lever for pivotal movement independently of the .pivotal movement of theV first lever, and a fuse link in said cartridge electrically connecting said terminals and normally holding said levers against movement by said springs, said second lever extending transversely relative to the axis of said cartridge when held by said fuse link.

19. In a circuit interrupting construction, an expulsion cartridge having at least one end open, in combinationwith a support for said cartridge, first and second conductor extracting levers, said first lever being pivotally mounted at one end on said support and normally extending to the open end of said cartridge and said second lever being pivotally mounted on the free end of said first lever and normally extending transversely of said cartridge adjacent said open end, biasing means urging said levers about their individual pivotal mountings and away from said open end, said biasing means urging said second lever about its pivotal mounting on said first lever irrespective of the pivotal movement ofsaid rst lever,

and a circuit interrupting conductor in said carltridge extending from said open end and holding said levers in their normal positions as aforesaid.

20. In a circuit interrupting construction, an expulsion cartridge having at least one end'open, in combination with a support including a terminal for said cartridge, first and second conductor extracting levers, said first lever being pivotally mounted at one end on said support andv normally extending to the open end ofsaid cartridge and `said second lever being pivotally mounted on the free end 0f said first lever and normally extending transversely of said cartridge adjacent said open end, biasing means urging said levers about their individual pivotal mountings and away from said open end, said biasing ,means urging said second lever about its pivotal mounting on said first lever irrespective of the pivotal movement of said first lever, a circuit interrupting conductor in said cartridge extending from said open end and holding said levers in their normal positions as aforesaid, and.Y

clamping means on said terminal connecting said conductor directly thereto.

2l. In a circuit interrupting constructionan expulsion cartridge having at least one end open, in combination with a support for said cartridge including a terminal for said cartridge, flrst and second conductor extracting levers, said first lever being pivotally mounted at one end on said support and normally extending to saidopen end of said cartridge and said second lever being pivotally mounted on the free end of' said first lever and normally extending transversely of said cartridge adjacent said open end, biasing means urging said levers about their individual pivotal mountings and away from said open end, said biasing means urging said second leverv about its said conductor directly thereto, said conductor f extending longitudinally across said second lever transversely of its pivotal connection with said second lever. f

22. In a fuse construction including an insulating support having a .pair of relatively spaced terminals with an expulsion fuse cartridge normally bridging said terminal, said cartridge having at least one end open, a mounting for said cartridge pivotally supported by said support, a first lever pivotally carried by said mounting adjacent the open end of the cartridge, said rst lever being biased for pivotal movement, a second lever pivotally mounted on the free end of the first lever, said second lever being biased for pivotal movement independently of the pivotal movement of the first lever, andy a fuse link in said cartridge electrically connecting said terminals and normally holding said levers against movement by said biasing means. l

23. In a fuse construction including an insulating support having a pair of relatively spaced terminals with an expulsion tube cartridge normally bridging said terminals, said cartridge having at least one end open, a mounting for said cartridge pivotally carried by said support, a first lever pivotally carried by said mounting adjacent the open end of said cartridge, a spring biasing the,k first lever for pivotal movement, a second lever pivotally mounted'on the free end of the rst lever, a second spring biasing the second leverv for pivotal movement independ-` ently of the pivotal movement of the irst lever, and a fuse link in said cartridge electrically connecting said terminals and normally holding said levers against movement by said springs, said first lever being substantially parallel to the axis of said cartridge when held by said fuse link, said second lever extending transversely relative to the axis of said cartridge when held by said fuse link.

24. In alfuse construction including an insulating support having a pair of relatively spaced terminals with an expulsion fuse cartridge n'ormally bridging said terminals, `having at least one end open, a mounting for said cartridge pivotally supported by said support, a first lever pivotally` carried by said mounting adjacent the open end of the cartridge, a meansbiasing the rst lever for pivotal movement, a second lever pivotally mounted on the free end of the first lever, a second means biasing the second lever for pivotal movement independently of the pivotal movement of the rst lever, and a fuse link in said cartridge electrically connecting said terminals and normally holding said levers against movement by said biasing means, said levers deriving their biasing power from different sources, neither lever depending upon the other and each operating regardless or whether or not the otheil operates.

WILLIAM O. SCHULTZ. 

